Secondary preselector



April 3, 1951 F. P. GOHOREL 2,546,998

SECONDARY PRESELECTOR Y Filed Feb. 14, 1947 3 Sheets-She et 1 MS MP INVENTOR. FERNAND I? GOHOREL ATTOR EY April 3, 1951 GOHOREL 2,546,998

SECONDARY PRESELECTOR is )2 g l INVENTOR. FERNAND F? GOHOREL ATTORNEY April 3, 1951 F. P. GOHOREL 2,546,993

SECONDARY PRESELECTOR Filed Feb. 14, 1947 5 Sheets-Shet 5 FIG. 4.

INVENTOR. FERNAND F? GOHOREL BY Wyk ATTORNEY Patented Apr. 3, 1951 SECONDARY PRESELECTOR Fernand P. Gohorel, Paris, France, assignor to International Standard Electric Corporation, New York, N. Y., acorporation of Delaware Application February 14,1947, Serial No. 728,633 In France May 5, 1946 1'7 Claims.

This invention relates to new and useful improvements in call-distributing arrangements for machine switching, e. g. telephone exchanges.

It is known that the distribution capacity of a group of lines outgoing from a selector having a. limited number of outlets can be increased by providing an intermediate non-numerical switch, a so-called secondary preselector, arranged to extend each of the outlets of the selector to a difierent group of lines.

In order to reduce the selection time, preselectors have been positioned on an idle line and moved when this line was seized by another pre selector. However, this necessitates the frequent and unnecessary operation of the secondary preselectors even during periods of light trafiic, and results in premature wearing out of the preselectors The object of the present invention is to lessen the operation of the preselectors while still retaining the advantage of preselection.

One of the features of the invention consists in an arrangement of the circuits of the preselectors and in such groupin of the preselectors that they will be operated only when all preselectors connected to the terminals of a group of selectors are standing on terminals of busy lines.

Another feature of the invention consists, in combination with the above arrangement, of means for preventing the movin of the preselectors when all the lines to which they have access are busy.

Another feature of the invention consists, in

combination with one and/or the other of the above features, to arrange the lines connected to the preselectors in pairs and to make it possible artificially to make busy the preselector standing on one of the lines when the other is selected and made busy.

1 In certain cases it may be desirable, and the present invention. contemplates the provision of means, to move the preselectors of a group of selectors before all the lines to which they have access are busy, because a call may be initiated before a preselector reaches an idle line.

Another feature of the invention consists of the means necessary for the moving of the preselectors when only a certain number of idle lines remains accessible, without operating the selectors connected. to the outlets of the respective group. of preselectors.

Various other features will appear from the following description given as an example without limitation, and with reference to the ap pended drawings, in which:

Fig. 1 shows the general layout of an arrangement of the preselectors according to the invention; Fig. 2 shows a circuit diagram that makes it possible to obtain the desired result;

Fig. 3 is a variant of Fig. 2 and is applicable to the case in which several outgoing lines can be temporarily associated with a common element; and

Fig. 4 illustrates the starting circuits for operating preselectors when only one or two idle trunks remain accessible, without starting the selectors connected to the outlets of the respective preselectors.

Fig. 1 illustrates two groups of selectors Si, 8'1, and S2, S'z, each having n outlets (five in the ex-S ample shown), and five groups of preselectors P1, P'i, P2, P'a P5, P's, each havin access to 12 lines. Trunk connections between the terminals of the selectors and the wipers of the pre-- selectors are made in accordance with well known arrangements in such a way that each outlet of a group of selectors is connected to a preselector that has access to different lines; each selector can accordingly have access to up lines.

A suitable device Cr prevents preselectors P1, P2, P3, P4, P5, which serve the first group of se lectors, from starting to hunt for an idle line unless the lines on which they are waiting are all busy. During this time a selector of the first group S1, S'i immediately can have access toan idle line over one of preselectors P1 to P5, and it is not necessary to set in motion any preselector. The same holds good for preselectors P'l to P's that serve the second group of selectors S2, S'2.

In Fig. 2 the relay contacts that are closed when the relay with which they are associated is energized, are designated by the letter T placed in front of the number of. the spring, and the relay contacts that are closed when the relay is not energized, by the letter-R. placed in front of the number of the spring. Furthermore, the contact springs associated with a certain relay are des-' ignated by one of the-numerals 1 to!) placed after the reference number of the relay.

It will first be assumed that the wipers of preselector P (Fig. 2) are standin on the terminals of an idle line; the idle potential is applied to bank contact TS of the selector S over wiper T? of the preselector and a resistance R61 individual to the idle line. Relay 5 becomes energized across resistance R61, and closes'at T5l the energizing circuit of relay 6.

When a selectorhunts for an idle trunk, its wipers stop on one leading to saidpreselector,

operating position as long as one of the relays v5- is energized, i. e. if said lines are not all busy.

Relay 2 then locks up over: battery, left-hand. winding of 2, TH, bank contact TS, andground Theconnection ofthe applied by the selector. selector to the line is efiected by contacts T22 and T24. At R23, relay 2 cuts out relay 3; and at T23 it completes the following circuit: battery, resistance, R62, T23, wiper RP and bank contact, wire rp multipled to the bank contacts of all the pre selectors of the same group, and in all the pr'eselectors of said group that are available and stopped on the same line, bank contact and wiper RP, R23, relay 3, contact rl associated with R,

battery. q

Relays 3 of these preselectors become energized. .If, among all the preselectors that serve the group of selectors in question, there is at least one available that is standing on an idle line,,i. e. on a line other than the one just seized by preselector P,.relays 2 and 3 of this preselector are in the resting position, and nothing happens. On the other hand, if all the preselectors that serve the group of selectors in question are either busy or standing on a line previouslyseized by another preselector, one of the relays 2 or 3 is I pulled up in each preselector; relay 2 ifthepreselector is busy, and relays if the preselector is standing on a busy line.

:The device CI or C2 of Fig. 1 which prevents the preselectors from starting to hunt for an idle line unless the lines on which they are riding are all busy, consists in Fig. 2 of the three wires a, b, and c of the preselectors serving the same group of selectors such as Si, Sf I of Fig. 1. As shown in Fig. 2, wires a, b, and c are part of preselector PI, 11, b', and c are part of preselector P2 and a", b", and c" are part of preselector P3 of Fig. 1. A ground is then applied to wire 0 over the following circuit: wire a, contact T25 of the preselector P that has just been seized by the selector, wire b, and, in a second preselector serving the group of selectors in question, wire a, T25 or T3l', wire b, and in a third preselector of the group, wire a, T25" or T3I", wire 2), operating contacts of one of the relays 2 or 3 of all the other preselectors of the group, to wire 0. This wire c is connected to the contacts 32, 32, 32" of allthe preselectors of this group, whereby at. this moment all the relays 4 [are operated'in the preselectors that have th'eirrelays 3 energized, i. e.

that are available and stopped on'a busy line.- In

each of these preselectors, relay 4 remains energized over T33 and T4! and closes the circuit of magnet R over: ground, T42, magnet R, point 9, TGI, battery. The magnet opens at rl the circuit of'relay 3. Relay 4 falls back, since the circuit of its two windings is opened at T32 and T33, re: spectively, and opens at T42 the circuit of magnet R, which releases its armature and causes the advance of the preselectors wipers to the next position.

The cycle is repeated if the-new; line at which the preselector wipers arrive-is-busy and if the lines at which the other preselectors ofv the same group happen to be standing are also busy. 7

Relay 6, which is grounded over contacts T5! in parallel with all relays 5, becomesenergized, and battery is applied to point 0 and, thus, to magnets R. When there is no longer any idle line, all the relays 5 are in the resting position, being short-circuited by the ground applied via the wipers TP, opening at T5! the circuit of relay 6, which falls back and prevents the advance of the preselectors that have access to this group of lines.

The variant of Fig. 3 shows two lines L1 and L2 multipled by wires M1 and M2 to all the preselectors of the same group. Relays I and 8 correspond to relay 2 of Fig. 2, relay 1 being connected to line i and relay 8 being connected to line 2, these relays operatin when the line is seized similarly to the way relay 2 of Fig. 2 operates. In the resting position,-idle potential is applied to the two lines over contacts 12 and 82 of relays T and 8, respectively associated with each line. When one of these lines becomes busy, e. gline L1, the busy ground applied by wiper TB of the preselector to bank contact ii of line L1 reaches also bank contact t2 of line L2 across contacts R12 and R82. Line L2 is thus artificially marked busy on the banks of the preselectors.

When a preselector stops on line L2, the follow ing circuit is completed: battery applied to wiper RP in the manner mentioned for Fig. 2, bank contact r1, RH, R85, bank contact r2, and'g'round across relay 3 of the preselector standing on line L2. From the above explanations it can be seen that if there is no longer any idle line accessible for the preselectorspthe preselector that is stand ing'on line L2 will advance by one step; from the standpoint of the operation of the preselector, the two lines behave as if they were a single line; Y

When the connection of the preselector to the line L1 is completed, relay 1 associated with line L1 becomes energized, opens its contacts RH and R12, dissociating the two lines, and thus permitting line L2 to operate independently of line Li. Line L2 can be marked available on the bank contacts of the preselectors independently of'the condition of line L1, and the advance of a preselector standing on line L2 is no'longer dependent on what happens on line L1.

In order to reduce operations to a minimum, it

is advisable that the lines associated with the same common element should not be disposed consecutively in the bank of the preselectors.

The circuit of Fig. 4 shows a variant of the circuit of Fig. 2, in that the hunting of the idle preselectors is started when less than all of the outgoing lines are busy. The relay 4 shown in Fig. 4 is the same relay 4 shown in Fig. 2. The variant of Fig. 4 shows only the circuits for controlling the starting of the preselectors. The chain circult of Fig. 2 (wires ab, ab, a"b") is replaced by a circuit that terminates in a double wound relay 9. Contacts 25, 3|, 25', 3!, 25", 3!", etc. are shunted by equal resistances r, r, r, etc. Relay 9 is so designed that the fluxes produced by the right-hand winding and the bottom left hand winding pull up armature 9! when the flux produced by the top left-hand winding is not high enough to counterbalance the flux produced by the bottom left-hand winding. If it 'is de sired to start when only a single line remains -As long as there are idle lines accessible to a group of preselectors, relays 5 of those lines are energized.

idle, the top left-hand winding is designedso that the flux it produces is equal to that pro duced by the bottom left-hand winding when the resistance of the chain circuit is reduced to the value 7*; if the start is to be efiected when two accessible idle lines remain, the top left-hand sags-4am winding is. designed ,sothat the flux thatit 'produces is equal, to, that produced by the bottom left-hand winding-when the resistance of the chain circuit is equal to 2r.

' Relay 9 is polarized by the right-hand co-il in such a way that, if the resistance of the chain falls below the equilibrium value (i. e. 0- or 1" in the two above cases) the armature is not pulled up-again by the resultant reverse flux.

What Ijclaim is:

1. In a telephone exchange system, a plurality of incoming lines terminatingin first switches, a plurality of second switches, outgoing lines sele'c'ted by-tthe second switches, means for rendering said outgoing lines busyptrunks connecting.

the first j to the second switches, magnets for operating the'first' and second switches, means .ibr'jghdering an idle second switch busy when Said second switch has selected an outgoing line that becomes busy and a chain circuit controlled by said last mentioned means for operating the magnets of idle second switches only when a predetermined number of the idle second switches has selected busy lines.

2. The system according to claim 1, and in which said predetermined number includes all the secondary switches which have selected busy outgoing lines.

3. The system according to claim 1, including means for preventing the operation of the magnets when all the outgoing lines are busy.

4. The system according to claim 1, including means for preventing the operation of the magnets when a predetermined number of said outgoing lines is busy. I

5. The system according to claim 1, and further comprising two relays in each second switch, means for energizing the first of said relays when the associated second switch is taken into use by a first switch, means for energizing the second of said relays when the outgoing line selected by an idle second switch is busy, the chain circuit including contacts of said second relays, and energizing circuits for the magnets of all said second switches controlled by all the second relays.

6. The system according to claim 1, and furthe comprising two relays in each second switch, means for energizing the first of said relays when the associated second switch is taken into use by a first switch, means for energizing the second of said relays when the outgoing line selected by an idle second switch becomes busy, the chain circuit including contacts of said two relays, and energizing circuits for all the magnets of the second switches controlled by all the second relays and one first relay.

7. In a telephone exchange system, a plurality of'g'roups of selectors, each having a multiple d terminal bank and wipers cooperating therewith, incoming lines terminating in said wipers, a plurality of groups of preselectors, each having" a multipled terminal bank and wipers normally positioned on idle terminals, outgoing lines terminating in the preselector bank terminals, means in each preselector responsive to a busy outgoing line, trunks connecting the banks of one group of selectors to the wipers of diiferent groups of preselectors, each preselector having a magnet for movingits wipers onto terminals of idle called lines, and means controlled by said busy lineresponsive means for operating the magnets fof a group of idle preselectors only when the wipers of a predetermined number of the preselectors of the group are standing on busy lines.

6, 8(I'he' system according reclaim m an 'iiin which the predetermined number includes all. 9. The system according to claim '7, and fun ther comprising'means for preventing the operation of the magnets of a group of idle preselectors when all the outgoing lines in their banks are busy. 1

10. The system according to claim 7, and further comprising means for preventing the operation of the magnets of a group of idle preselectors when a predetermined number of outgoing lines in their banks are busy.

11. The system according to claim '7, and'further comprising two relays in each preselector, means for energizing the first of said relays when the preselector is taken into'use'by a selector,

means for energizing the second of said relays when the outgoing line on which an idle preselector is standing is busy, and energizing circuits for the magnets of all idle preselectors belonging to the same group controlled by the second relays of all idle preselectors cf the group. I

12. The system according to claim 7, and further comprising two relays in each preselector, means for energizing the first of said relays when the preselector is taken into use by a selector, means for energizing the second of said relays when the outgoing line on which an idle preselector is standing is busy, and energizing circuits for the magnets of all idle preselectors belonging to the same group controlled by the second relays of all idle preselectors of the group and the first relay of one.

13. The system according to claim 7, and further comprising two relays in each preselector,

means for energizing the first of said relays when the preselector is taken into use by a selector, means for energizing the second of said relays when the outgoing line on which an idle preselector is standing is busy, energizing circuits for the magnets of all idle preselectors belonging to the same group controlled by the second relays of all idle preselectors of the group and the first relay of one, and means for preventing the closure of said energizing circuits when all the outgoing lines are busy which terminate .in the preselector banks.

14. In a telephone system, a plurality of incoming lines terminating in first switches, second switches, magnets for operating the first and second. switches, trunks connecting the first to the second switches, outgoing lines selected by the second switches and arranged in pairs, means for rendering the second one of the pair of lines busy to the first switches when the first line of the pair is selected by a second switch, and means for removing the busy condition from the first line of the pair when the connection with the second line of the pair has been established.

15. In a telephone system, a plurality of selectors, each having a multipled terminal bank and Wiper cooperating therewith, incoming lines terminating in said wipers, a plurality of preselectors, each having a multipled terminal bank and wipers normally positioned on idle terminals, trunks connecting the wipers of said preselectors with terminals of said selectors, outgoing lines terminating in the preselector banks and arranged in pairs, means for rendering the second outgoing line of the pair busy to the selectors when the preselector selects the first outgoing line of the pair, and means for removing the busy condition from th second outgoing line when the preselector has made connection with the first outgoing line.

16. In a telephone system, a plurality of incoming lines terminating in first switches, a plurality of second switches, magnets for operating the first and second switches, trunks connecting the first to the second switches, outgoing lines selected by the second switches, means for rendering an idle second switch busy to the first switches when it has selected a busy outgoing line, means for operating the magnets of the idle second switches only when a predetermined number of idle second switches have selected busy outgoing lines, and relay means common to the outgoing lines for preventing the operation of the magnets of idle second switches when all the outgoing lines are busy.

17. In a telephone'system, a plurality of incoming lines terminating in selectors, a plurality of preselectors adapted for selection by the selectors, trunks connecting the terminals of the selectors with the wipers of the preselectors, magnets, wipers and terminal banks for the selectors and the preselectors, outgoing lines adapted to be 8 selected by the preselectors, an idle preselector being busyto the selectors when the wipers of the idle preselector are resting on the-bank terminals of a busy outgoing line, means for operating the magnets of idle preselectors only when the'wipers of a predetermined number of idle preselectors are resting on busy outgoing lines, and relay means common to the outgoing lines for preventing the operation of the magnets of idle second switches when all the outgoing lines are busy."

I FERNAND P. GOHOREL.

REFERENCES [CITED The following references are of 'record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,559,736 Bellamy Nov..3, 1925 20 1,645,972 Rousseau Oct. 18, 1927 1,922,237 Escott Aug. 15, 1933 Matousek June 22, 1943 

